|Year : 2016 | Volume
| Issue : 1 | Page : 21-25
Corneal endothelial cell count following femtosecond laser-assisted cataract surgery versus conventional phacoemulsification
Yasser El-Zankalony1, Lamia S Elewa2, Safaa S.M. Saleh2
1 Lecturer of Ophthalmology, Ain Shams University, Cairo, Egypt
2 Assistant Professor of Ophthalmology, Ain Shams University, Cairo, Egypt
|Date of Submission||24-Aug-2015|
|Date of Acceptance||27-Nov-2015|
|Date of Web Publication||21-Oct-2016|
Lamia S Elewa
Ain Shams University, Cairo
Source of Support: None, Conflict of Interest: None
The aim of this work was to study and compare the safety and efficacy of femtosecond laser-assisted cataract surgery versus conventional phacoemulsification cataract extraction on the corneal endothelial cell count.
The study design was a prospective, comparative one.
Participants and methods
Fifty eyes underwent femtosecond laser-assisted cataract surgery and 50 eyes underwent conventional phacoemulsification between March 2014 and December 2014 at Ain-Shams University Hospitals and Magrabi Eye Institutes. In each group, 50 eyes (50 patients) underwent cataract surgery using either femtosecond laser-assisted (Alcon LenSx Laser) (the femtolaser group) or conventional phacoemulsification (the phaco group). Femtosecond laser-assisted cataract surgery involved anterior capsulotomy and lens fragmentation based on optical coherence tomography-guided treatment mapping. Conventional procedure involved manual continuous curvilinear capsulorrhexis. Both procedures were completed by means of standard phacoemulsification and insertion of an intraocular lens. Endothelial cell count was measured with a NIDEK Specular Microscopy (CEM-530) preoperatively, and at 1 day, 1 week, and 1 month postoperatively. Main outcome measures included effective phacoemulsification time, intraoperative complication rates, and corneal endothelial cell count.
Effective phacoemulsification time was reduced by 38% in the femtolaser group (P < 0.0001). All cases treated with the femtosecond laser achieved complete capsulotomy. There was one posterior capsule rupture in the femto group and two in the phaco group (0.5%; not significant). There was no statistically significant difference as regards intraoperative complications between the two groups. Postoperatively, there was a significant decrease in central corneal endothelial cell count in both groups compared with preoperative values. The endothelial cell count was significantly higher in the femtolaser group at 1 day, 1 week, and 1 month follow-up.
Femtosecond laser-assisted cataract surgery appears to be as safe as conventional cataract surgery, with lower effective phacoemulsification time and hence less corneal endothelial cell loss.
Keywords: cataract surgery, endothelial count, femtosecond, phacoemulsification
|How to cite this article:|
El-Zankalony Y, Elewa LS, Saleh SS. Corneal endothelial cell count following femtosecond laser-assisted cataract surgery versus conventional phacoemulsification. J Egypt Ophthalmol Soc 2016;109:21-5
|How to cite this URL:|
El-Zankalony Y, Elewa LS, Saleh SS. Corneal endothelial cell count following femtosecond laser-assisted cataract surgery versus conventional phacoemulsification. J Egypt Ophthalmol Soc [serial online] 2016 [cited 2023 Jan 28];109:21-5. Available from: http://www.jeos.eg.net/text.asp?2016/109/1/21/192747
| introduction|| |
With the advent of femtosecond laser-assisted cataract surgery, a highly controlled and reproducible capsulotomy, efficient lens fragmentation or liquefaction, and precise creation of a corneal incision became possible ,. Corneal edema is one of the most frequent early postoperative complications of phacoemulsification, which can sometimes lead to permanent and serious visual disturbances. Postoperative corneal swelling and endothelial cell loss are related to many factors, including phacoemulsification time and energy, cataract density, corneal pathology, anterior chamber depth, axial length, ocular trauma, mechanical and heat injury, phacoemulsification technique, experience of the surgeon, and use of a viscoelastic material .
In our study, we aimed to report the effective phacoemulsification time, intraoperative complication rates, and analyze the postoperative endothelial cell count, following femtosecond laser-assisted phacoemulsification compared with conventional phacoemulsification.
| Patients and methods|| |
This prospective study was performed at the Departments of Ophthalmology of Ain-Shams University Hospitals and Magrabi Eye Institute between March 2014 and November 2014.
The study was designed in accordance with the rules of Ain-Shams University's ethical committee and adhered to the tenets of the Declaration of Helsinki.
One hundred eyes of 60 patients with cataract who were candidates for phacoemulsification and intraocular lens implantation and met the inclusion and exclusion criteria were enrolled after informed consent was obtained.
The inclusion criteria were as follows: age between 50 and 70 years, axial length between 22.0 and 24.0 mm, manifest refractive spherical equivalent between +2.0 and −5.0 D, nuclear cataract of grade 2–3 (nuclear opalescence 3–4) according to the Lens Opacity Classification System (LOCS III) classification, and corneal endothelial cell count greater than 1600/mm2. The exclusion criteria were as follows: low cooperation of patients, dense or white cataract, corneal opacities, anterior segment abnormalities, poor pupillary dilation, and previous anterior or posterior segment surgery.
The enrolled patients were randomized into two groups: the femtosecond laser-assisted cataract surgery group, which included 50 eyes of 50 patients (the femtolaser group), and the conventional phacoemulsification, which included 50 eyes of 50 patients (the phaco group).
All patients underwent a complete ophthalmologic evaluation including best-corrected distance visual acuity (BCVA) including manifest refraction, slit-lamp examination, and intraocular pressure measurement. Biometry was performed using a noncontact optical low-coherence reflectometer (Lenstar LS 900; Haag-Streit AG, Koeniz, Switzerland). Cataract grade, nuclear density, and opalescence using the LOCS III  were reported. Central endothelial cell count was measured with a NIDEK-CEM Specular Microscope CEM-530 (NIDEK Co. Ltd, Tokyo, Japan) ([Figure 1]).
All operations were performed under topical (proparacaine HCl 0.5%) or local anesthesia by two surgeons. Pupillary dilation was achieved with the instillation of one drop of tropicamide 0.5% every 15 min, three times before surgery.
In the phaco group, 2.8-mm clear corneal and side-port incisions were made with a disposable keratome (Alcon Laboratories Inc., Fort Worth, Texas, USA). Continuous curvilinear capsulorrhexis was performed with a cystotome and a capsular forceps, and a divide-and-conquer phaco technique was used.
In the femtolaser group, the LenSx Femtosecond Laser System (Alcon LenSx Inc., Aliso Viejo, California, USA) was used to generate a 4.75-mm capsulotomy, lens fragmentation in a cross pattern, and two corneal incisions (a 2.8-mm two-plane main incision and a 1.0-mm single-plane side-port incision) ([Figure 2]).
|Figure 2: LenSx Femtosecond Laser System (Alcon LenSx Inc., Aliso Viejo, California, USA) was used to generate a 4.75-mm capsulotomy, lens fragmentation in a cross pattern.|
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Following femtosecond laser treatment, the corneal incisions were opened with a blunt spatula and the anterior chamber was filled with a viscoelastic material (Provisc; Alcon Laboratories Inc.). Following hydrodissection, standard phacoemulsification was used to remove the nucleus prechopped by the laser. In both groups, the Infinity phaco system (Alcon Laboratories Inc.; vacuum: 380 mmHg fixed, aspiration rate: 35 ml/min fixed, bottle height: 110 cm) was used. After cortex removal and implantation of the one-piece hydrophobic acrylic intraocular lens (IOL) (Alcon Laboratories Inc.), the viscoelastic material was completely removed by means of irrigation–aspiration. Gentle hydration of the main corneal incision was performed in both groups.
Demographics are shown in [Table 1], and preoperative values are presented in [Table 2].
|Table 2: Preoperative endothelial cell density and surgical parameters of eyes in the femtolaser group versus the phaco group|
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BCVA, slit-lamp examination, and intraocular pressure measurement and central endothelial cell count were repeated at 1 day, 1 week, and 1 month postoperatively.
Medcalc software (Ostend, Belgium) was used due to normality of data. Descriptive statistics were presented as mean and SD. For group comparisons of continuous variables, the independent sample t-test was used. To analyze changes in central corneal thickness over the time course, a repeated-measures analysis of variance was used. To test the effect of type of surgery on postoperative central corneal thickness, a multivariable regression analysis was performed. In all analyses, P-value less than 0.05 was considered statistically significant.
| Results|| |
Patient demographics were similar in both groups. The mean age was 66.3±7.5 years (range: 54–70 years) in the femtolaser group and 64.5±6.8 years (range: 50–70 years) in the phaco group (P>0.5).
We included patients with similar cataract density (LOCS III, grade 1–3). Nuclear opalescence was not significantly different between the two groups. Manifest refractive spherical equivalent did not differ significantly between groups; it was −2±(−0.5) D in the femtolaser group and −1±(−3.5) D for in phaco group.
There was no statistically significant difference as regards intraoperative complications between the femtolaser group and the phaco group. There was one posterior capsule rupture in the femtolaser group and two in the phaco group (P>0.5; not significant). All cases treated with femtolaser achieved complete capsulotomy.
Effective phacoemulsification time was reduced by 38% in the femtolaser group (P<0.0001). Twenty-one (42%) eyes in the femtosecond group versus two (4%) cases in the phaco group had zero effective phacoemulsification time (P<0.0001).
The corneal endothelial cell count preoperatively and 1 month postoperatively was measured and compared ([Table 2]). Postoperatively, there was a significant decrease in central corneal endothelial cell count in both groups compared with preoperative values, with statistically significant differences between the two groups at 1 day, 1 week, and 1 month follow-up (Student's t-test and paired Student's t-test, P<0.05).
By the end of the follow-up period, the mean change in endothelial cell count was –93±107 and −216±129 cells/mm2 in the femtolaser and the phaco group (a 3.3 and 7.8% decrease), respectively.
Visual acuity (VA) and BCVA increased significantly postoperatively in both groups during the follow-up period (P<0.05). However, a slightly significant difference between the two groups was noticed at the early follow-up period, where the femtolaser group showed better VA at first postoperative day ([Table 3]).
| Discussion|| |
Femtosecond lasers may revolutionize the way cataract surgery is performed, with promising preliminary results showing precise and self-sealing corneal incisions, consistently accurate capsulorrhexis , which optimizes adequate centration and positioning of an IOL, decreased phacoemulsification energy, decreased endothelial cell loss, and lower incidence of postoperative cystoid macular edema ,,.
The potential benefit of femtosecond laser treatment is from the subgroup of patients requiring no phacoemulsification energy; hence, there is a decreased incidence of postoperative corneal endothelial cell loss.
In this study, there was a significant reduction in effective phacoemulsification time by 38% in the femtosecond group (P<0.0001). Twenty-one (42%) eyes in the femtolaser group versus two (4%) cases in the phaco group had zero effective phacoemulsification time (P<0.0001). This is in agreement with previous studies conducted by Nagy et al. Abell et al. also reported a higher reduction in effective phacoemulsification time of almost 70% in their larger study on 200 eyes that underwent femtosecond laser cataract, with a decreased incidence of postoperative corneal endothelial cell loss.
We achieved 100% complete capsulotomy in the femtolaser group and there was one posterior capsule rupture in the femtolaser group and two in the phaco group (0.5%; not significant). In the study by Abell et al., there was only one posterior capsular rupture in both groups within the first 200 cases. Nagy et al. reported that a capsulotomy architecture is more likely to have the correct diameter and shape when compared with manual techniques and it reduces the pulling/stretching forces that are placed upon the lens zonules during manual capsulorrhexis.
We focused on the effect of femtolaser on the postoperative corneal endothelial count. Postoperatively, there was a significant decrease in central corneal endothelial cell count in both groups compared with preoperative values, with statistically significant differences between the two groups, and the corneal endothelial cell count was higher in the femtolaser group at 1 day, 1 week, and 1 month follow-up (Student's t-test and paired Student's t-test, P<0.05). Patients in the femtolaser group showed better VA on first postoperative day.
Takács et al. demonstrated less corneal swelling and endothelial cell damage in patients undergoing femtosecond laser-assisted cataract surgery than in those undergoing a conventional phacoemulsification technique at all visits.
Mastropasqua et al. also found a lower central endothelial cell loss at 7 and 30 days in the femtosecond laser CCI group compared with the manual CCI group. In addition, femtosecond laser showed a better morphology (lower percentage of epithelial and endothelial cell gaping).
Limitations of our study were as follows: first, there was a lack of analysis of endothelial cell morphology; second, patients were not matched according to lens density, although mean values did not differ significantly between groups; and, finally, randomization was performed by a surgeon and not using randomization tables.
To conclude, femtosecond laser-assisted cataract surgery appears to be as safe as conventional cataract surgery, with reduced ultrasonic energy and lower effective phacoemulsification time and hence less corneal endothelial cell loss.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]